While targeted gene ablation methods have matured to the point that investigators can confidently design experiments that will totally eliminate production of any protein, over-expression and ectopic expression methods has not significantly evolved since the production of the first transgenic mice in the late 1970s by DNA microinjection in fertilized mouse oocytes. Because expression after random integration of multiple copies of the transgene in the mouse genome is often unpredictable, this simple microinjection method has become inadequate for many purposes. We propose here to develop a system for high-throughput transgenic mouse production that will generate animals that express transgene in a ubiquitous, tissue-specific or inducible manner at predictable levels because the transgenes will be inserted as single-copies at defined sites in the mouse genome. This new system will be based on methods to perform site-specific chromosomal integrations using Recombinase-Mediated Cassette Exchange directly in fertilized mouse oocytes, on the development of standardized integration sites, and on the construction of RMCE-enabled indexed cDNA libraries. Once frilly implemented, this new system will enable investigators to study the function of any known mouse or human cDNA by expressing ectopically, or at precisely defined graded levels of over-expression with minimal efforts and at minimal costs.